Adapt tests to changes in youtube's "Most Popular" channel

test/test_youtube_lists.py

@@ -97,7 +97,7 @@ class TestYoutubeLists(unittest.TestCase):
         self.assertTrue(len(result['entries']) > 90)
         #test autogenerated channel
         result = ie.extract('https://www.youtube.com/channel/HCtnHdj3df7iM/videos')[0]
-        self.assertTrue(len(result['entries']) > 20)
+        self.assertTrue(len(result['entries']) >= 18)
 
     def test_youtube_user(self):
         dl = FakeDownloader()